


The Origin of Our Universe and Everything We Know to be True

by an3m1c



Category: Haikyuu!!
Genre: Canon Compliant, Character Study, Childhood Friends, Childhood Memories, Childhood Sweethearts, Domestic Bliss, Domestic Fluff, Fluff, Fluff and Angst, Fluff and Humor, IVE NEVER WRITTEN ANYTHING SO SOFT IN MY LIFE, M/M, Mutual Pining, Oblivious Iwaizumi Hajime, Oblivious Oikawa Tooru, Post-Canon, Pre-Canon, So so much fluff, THERES ANGST EVENTUALLY IF YOU SQUINT BUT ITS JUST THERE TO MAKE THE FLUFF FLUFFIER, THEYRE SO (CHICKEN) TENDER, Tooth-Rotting Fluff, True Love, YALL GETTING IWAOI THROUGHOUT THE YEARS AAAAHH
Language: English
Status: In-Progress
Published: 2021-02-14
Updated: 2021-02-14
Packaged: 2021-03-15 11:27:13
Rating: General Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 3,315
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/29435307
Author URL: https://archiveofourown.org/users/an3m1c/pseuds/an3m1c
Summary: They had a love that was written in the stars.And it begins with a kick to the shins.*********************************************The story of Iwaizumi and Oikawa's lives and everything they know to be true.
Relationships: Iwaizumi Hajime & Oikawa Tooru, Iwaizumi Hajime/Oikawa Tooru
Comments: 12
Kudos: 33





	The Origin of Our Universe and Everything We Know to be True

**Author's Note:**

> [slams first on table] baby iwaoi!!!!!!

It begins with a kick to the shins. 

Iwaizumi Hajime is six years old and mid-sleepover with his current best friend, Oikawa Tooru. They’re both tall for their age - though Iwaizumi will always remind Oikawa he’s five centimeters taller - but they’re both still small enough to share a futon. Iwaizumi's okaa-san insisted on setting up a spare, but he told her no. Autumn evenings were chilly in Miyagi, and Oikawa was warm. He thought they’d be able to fight off the cold together in a shared futon.

Right now Iwaizumi wishes he had accepted his okaa-san’s offer.

“Ow! Oikawa!” Iwaizumi doesn’t care that he’s yelling in the middle of the night. It’s not his fault that Oikawa has a powerful kick.

“Hmm?” Oikawa slowly rolls over to face Iwaizumi, eyes closed with the intent of sleeping through the ordeal. Iwaizumi refuses to let him. Oikawa just kicked him in the _shin_ ; the least he'll be getting tonight is a piece of Iwaizumi's mind.

“Why’d you kick me? That hurt.” Iwaizumi winces from the ghost of Oikawa’s kick.

“Wha- I kicked you?” Oikawa squints at Iwaizumi, trying to see his friend through the dark and the haze of his sleep.

“Yeah, really hard.'' Leg still throbbing, Iwaizumi’s awake enough to think about why Oikawa would do such a thing. His voice comes out soft when he lands on an answer.

“Did you have a nightmare?” 

This isn’t their first sleepover. Iwaizumi and Oikawa have been friends since they were three years old. That’s half of their lives so far (or “forever” as Oikawa once described it). Sleepovers were a common occurrence. When they first began, they would bring a little backpack to the other’s house, neatly packed with all the essentials. For Iwaizumi, this included a red toothbrush, a Godzilla action figure, and sweets for Oikawa. Oikawa preferred a blue toothbrush, a Vabo Chan plushie, and a volleyball. 

Now that forever has passed, both of them have dedicated a single drawer in each of their rooms to the other. It began because Oikawa always forgot his pajamas at Iwaizumi’s house, and Iwaizumi kept forgetting his action figures at Oikawa’s. 

Iwaizumi told himself it was for function, but gradually he found himself wearing Oikawa’s funny shirts, Oikawa found himself playing with Iwaizumi’s toys, and their single drawers expanded to their bedroom floors in the form of volleyballs and scattered knee pads. 

These days, they found each other side-by-side in the dark sharing a futon at least once a week. As Iwaizumi became acquainted with Oikawa, he learned that Oikawa was prone to nightmares that resulted in kicking. As Oikawa became stronger from playing volleyball, so did his kicks. Still, Iwaizumi insisted on sharing a futon.

They’ve come a long way since their first encounter where Oikawa hid behind his okaa-san’s legs, intimidated by the boldness of the spiky-haired boy and his outstretched hands. Despite his shy nature, Oikawa was curious about his world which slowly took the shape of a boy named Iwaizumi. 

In return, Iwaizumi found what true companionship meant. Iwaizumi never had a shortage of friends, but he never had a friend he wanted to spend every day with. He drew Oikawa out of his quiet demeanor with wild exaggerations and random nature facts until he filled their lives with forest adventures with twinkling laughter. It wasn’t long before they found themselves together all the time, and Iwaizumi was determined for it to stay that way. And that included soothing Oikawa after his nightmares, even after he kicked him in the shin.

So Iwaizumi, in all his six-year-old wisdom, softens his voice as if trying to imitate the comfort of a hug. “Come on Oikawa, you don’t have to be embarrassed about nightmares. You’re not a baby anymore.” He imagines Oikawa pouting in the dark (his intuition is correct).

“I-,” Oikawa sniffs. “Yeah, I had a nightmare.”

Iwaizumi’s eyes adjust to the dark just enough to see the moonlight reflect off the tears on Oikawa’s face. He almost wishes he couldn’t see them. Watching his best friend cry makes his chest hurt in a way he did not yet know how to remedy.

“Do you want to talk about it?” He scootches closer.

Oikawa wipes his eyes with the edge of his blanket, doesn’t think about how gross it is, doesn’t think as he reaches out for Iwaizumi’s hand with only the moonbeam to guide him. His slim fingers wandering across the ridges and valleys of their shared comforter, adrift and a little unsure in the space between them.

So Iwaizumi’s hand finds his first, tenderly interlacing his fingers with Oikawa’s.

Oikawa lets out a shaky breath, inhales and exhales a few times to steady his trembling heart. 

“In my dream- In my dream we were playing volleyball together. Passing and stuff like Coach tells us to. And then,” his voice quivers.

Iwaizumi squeezes his hand. “Then what?”

“I tried to pass you the ball. But you weren’t there,” his voice cracks, and Iwaizumi imagines tears retracing Oikawa’s cheeks. “Iwaizumi, you weren’t there and I got scared and kept running around trying to find you, but I couldn’t wake up or stop running and-”

Iwaizumi interrupts Oikawa with a hug, crushing their bodies together, hands still intertwined, elbows knocking against each other. It’s clumsy and rushed, but it’s warm - it’s what Oikawa needed.

“I’m here Oikawa,” Iwaizumi says. His words settle onto Oikawa, soothing his anxieties. “I’m not leaving or running away. Okay? I promise.” He feels Oikawa nod into his shirt, fresh tears seeping into the fabric. Feeling his best friend cry, Iwaizumi’s heart turns in on itself, and he pulls away to get a proper look at Oikawa. 

Oikawa’s lips quiver as he attempts to get out his next words.

“Really?”

Iwaizumi looks into his eyes, hoping they convey everything he’s feeling despite the dark.

“Yeah really.”

His words cue another flood of tears, Oikawa burying his face into the blanket to muffle his crying. Iwaizumi’s brows furrow, and his hand, still holding Oikawa’s, goes stiff. Confusion and worry settle over him as his mind tries to make sense of the boy in front of him. 

He doesn’t know if he wants to shake him or hold him close until they share the tears that Oikawa seems to have an endless supply of. Trapped between indecision and caring too much, Iwaizumi settles on squeezing his best friend’s hand tighter, rubbing his thumb in circles over the back of Oikawa’s hand just like his okaa-san did for him hoping to bring some semblance of comfort to Oikawa.

“Shhh,” Iwaizumi’s eyes follow every shudder that’s projected by Oikawa’s back. “It’s okay,” he whispers, just barely audible amidst Oikawa’s crying. 

“It’s okay” is another one of those things Iwaizumi hears adults say to each other all the time. He’s not sure what “it” is, but right now he wants ”it” to be whatever is causing Oikawa to cry. Iwaizumi wishes to the night sky that “it” is everything, that everything will be okay for Oikawa because his best friend deserves things that cause his eyes to light up and make him smile uncontrollably.

Iwaizumi always looked out for Oikawa like this. At first glance, Oikawa appeared to orbit around Iwaizumi, but it was actually Iwaizumi who gravitated towards Oikawa. Iwaizumi had an easy time making friends but what he wanted was to hang out with the quiet kid with fluffy brown hair that always fell in his eyes, determined to see beyond the wayward glances and nervous leg bouncing. 

Although Oikawa was no longer quite as timid, he still had that same fluffy head of hair and eyes that could illuminate the sky. Iwaizumi wonders when Oikawa’s eyes would be dry enough to do that again.

As Oikawa’s watery breaths slowly returned to normal, his eyes peeked out of his little nook, face half-obscured by their shared blanket. 

_He’s like a cute little puppy,_ Iwaizumi thinks to himself and then immediately hurls his thoughts into the dark as his face grows warm (he blames this on the blanket).

“Hey Iwa-chan?” 

_Iwa-chan?_

That was… new. Oikawa had never been one for nicknames before. He always insisted on calling Iwaizumi by his family name. _“He’s a little shy. He needs some time to warm up to people,”_ Oikawa’s okaa-san once said. The way Oikawa said “Iwa-chan” made Iwaizumi feel small, and not like the tallest kid in class (another fact he always liked to point out to Oikawa). Like he could be held in someone’s pocket. 

Iwaizumi likes to be held. He likes piggy-back rides and hugs and hand-holding. Yet, something about this made him feel what can best be described, for now, as prickly and itchy. Iwaizumi now has an impossible-to-scratch itch. 

“What if-” he gives Iwaizumi a look that makes him wonder if all the crying really did turn his friend into a small dog. 

“What if we got married?”

_What?_

Iwaizumi’s eyes widen as his brain processes Oikawa’s five words, each one yanking him out of his once-groggy state.

Well, this certainly wasn’t something school had prepared him for.

“I- isn’t that something adults do? Like your onee-chan?” Iwaizumi stumbles over his words and blames it on lack of sleep.

“I guess.” Oikawa shrugs from underneath their blanket. His small body wiggles around, and his eyes wander searching for something right in front of him. 

“But when people get married, they stick together, right? Forever? That’s what my onee-chan says when she talks about her dream wedding to her friends.”

_Ah,_ Iwaizumi connects the pieces in his head. There’s no need for Oikawa to complete his thoughts even though Iwaizumi is sure his friend has many more ridiculous ideas (though, this one might surpass starting volleyball as Oikawa’s most outlandish idea yet). Having known each other for most of their lives meant that they grew up together and helped each other grow too. They knew when the other person needed help and how to complete the other’s thoughts.

“But,” Iwaizumi sighs. “Do we _really_ need to get married to stick together?”

“No,” Oikawa pulls the covers down to reveal a pout ( _he totally did that on purpose_ , Iwaizumi thinks). “But it sounds fun. My onee-chan told me weddings have really big cakes too.”

Iwaizumi does not know very much about weddings, but he does know that Oikawa has a sweet tooth. He is also not immune to the idea of a wedding cake.

“Well, would a wedding and wedding cakes make you happy?” Iwaizumi asks.

Oikawa’s eyes twinkle, and the residual tears turn the bits of light reflected in his eyes into stars. 

There’s no trace of a pout left on his face.

Iwaizumi accepts this as a yes. 

“Okay, then let's get married.”

“Not right now Iwa-chan!” It was that name again. Oikawa’s brand new nickname for Iwaizumi that made his cheeks warm and prickly both of the times he used it. He doesn’t know how to stop the tingling sensation and decides then that he does not like the feeling.

“Don’t call me that!”

“Hmph! I guess Iwa-chan doesn’t want to marry me afterall.”

“No, Oikawa! That’s not what I meant!”

“But I want to call you Iwa-chan!”

Another pout. 

God, Iwaizumi hates it when Oikawa pouts because Oikawa knows how to use it against people. Iwaizumi has seen it bring his strictest teachers under Oikawa’s sympathy, and, even after a lifetime with Oikawa, Iwaizumi still has not developed any resistance towards it.

He takes in a deep breath. “Fine.”

Oikawa’s pout disappears like clockwork.

“You can call me Iwa-chan only if I get to marry you.”

Oikawa breaks into a smile so radiant that for a moment Iwaizumi believes he can see in the dark.

“Yay! Iwa-chan wants to marry me!” Oikawa exclaims.

“Shhh! You’re going to wake the whole house,” Iwaizumi whispers.

“Let’s get married now.” Oikawa squeezes his hand, their fingers now likely glued together for the rest of eternity.

“Right now?” 

“Yeah right now!”

“Shouldn’t we wait until we’re adults?”

“But Iwa-chaaan,” Oikawa whines. “I don’t want to wait that long. I want to get married nooooow!”

Maybe it had something to do with being an only child, but Iwaizumi has definitely developed an immunity towards Oikawa’s whining. It took some time, but now Iwaizumi knows how to stand his ground. Never again will he fall victim to “but just one more set pleeaase” from Oikawa.

“No Oikawa. We should get some sleep first.”

“Fine, I’ll wait until tomorrow.”

“That’s still too soon.”

“Then let’s get married when we’re 12! That’s how old you are plus how old I am.”

Though Iwaizumi can’t argue with Oikawa's math, he’s pretty sure most adults don’t get married at 12 years old. He’s not even sure that 12 year olds could be considered adults.

“How about 30?” He proposes to Oikawa.

“30?! We’d have to wait forever!”

Iwaizumi doesn’t give a reason for why he chooses the number 30. It felt right. Good things involve the number three - three sets in a match, Oikawa was three when he overcame his shyness and said his first words to Iwaizumi, they were three years old when they had their first sleepover - and the zero reminded him of their favorite pastime. 

“I’m okay waiting forever for you.”

Oikawa’s bottom lip twitches just enough to make Iwaizumi wonder what he said wrong this time.

“That’s a lot of waiting Iwa-chan.”

“I’m patient. How else would I deal with you during practice?” Iwaizumi says holding back the giggles in his chest.

“Iwa-chan is so mean! Hmph, I’m not taking your family name then.”

“My family name?” Iwaizumi questions. Clearly Oikawa was more well-versed in the intricacies of marriage. He wonders if he missed a lesson in class, or maybe these are things one only learns by having an onee-chan.

“Silly Iwa-chan.” He was really going to make the most out of this new nickname. “When people get married they change their family names.”

_Oh, that’s interesting_ , Iwaizumi thinks. He didn’t realize that there was anything else to marriage besides wedding cakes. Then again, he doesn’t know much about marriage and weddings besides what Oikawa has told him.

“So does that mean I take your family name? Switching family names seems fair,” Iwaizumi questions.

“I suppose so,” Oikawa’s eyes widen with a sudden revelation. “Wait! But then you won’t be Iwa-chan anymore!” 

“Don’t be silly, Oikawa,” Iwaizumi gently nudges his feet against Oikawa’s. “I’ll still be me.”

“But I’ve always wanted to be an Iwa-chan.” 

(“Always” being the entirety of their current late-night conversation.)

“What if I don’t want to call you Iwa-chan?” He’s still unhappy with the way the nickname makes his cheeks feel, and he really doesn’t like the thought of having to hear it twice as often.

“Fine.”

Pout.

“Call me Tooru then.”

Well, that brings a fire to his face that he hasn’t felt since the last time he caught a fever (could he have really caught a cold?). Oikawa is so close to him that Iwaizumi is sure he could see everything wrong with him - his spike in temperature, the twitch of his eyelid, every pounding heartbeat. He wasn’t keen on the idea of someone knowing him like that, and he’s suddenly grateful for the cover of the night.

“No.” He says, intent on ending the conversation before it gets worse.

“Fine, _Hajime_.”

Of course it got worse.

Now Iwaizumi is crawling in his own skin. His heart threatens to escape towards Oikawa, tugging his body along with it like a reluctant passenger. This lack of control irks him, makes his tongue forget how to form words, causes him to sweat through his pajamas. 

He stares at his friend straight in the eyes. Iwaizumi knows exactly what he wants to say. He’s an only child who spends a lot of time around adults. If there’s one thing adults are good at, it’s handling problems, and Iwaizumi’s current problem is Oikawa making him uncomfortable in his own home. 

He prepares his best serious face, downturns his mouth into a (very serious) frown, and prepares his words on the tip of his tongue the same way Oikawa prepares his sets ( _Stop thinking about Oikawa!_ He screams in his head).

He fires his words.

“Shut up Shittykawa!”

Iwaizumi is an only child who spends a lot of time around adults, and adults use very colorful language. Looking at Oikawa’s wide eyes, gaping mouth, and word-less response, he silently thanks his okaa-san for accidentally introducing The Word to him.

Unfortunately, Oikawa recovers quickly.

“Iwa-chan has a potty mouth!”

“You’re the one who’s all snotty and gross!”

“No! You’re the one who’s gross.”

“How am I gross? I haven’t even done anything.”

Oikawa holds up their hands, fingers still intertwined. “Iwa-chan’s hands are sweaty!”

Iwaizumi looks at their hands. His is pressed close to Oikawa’s, their fingers glued together by tears and sweat. Oikawa was right, it is very gross, but Iwaizumi doesn’t want to stop holding Oikawa’s hand and- _oh gosh, they were still holding hands_. 

“F- fine then!” He stumbles over his words. “We don’t have to hold hands anymore, Shittykawa.”

“Nooo Iwa-chan,” his hand tightens around Iwaizumi’s. There’s no escaping now. “I like holding your hand and we need to practice holding hands even when we’re gross and sweaty because that’s what married people do.”

This time, Iwaizumi pouts. “Go to sleep Shittykawa. You think too much.”

“Hmph,” Oikawa pulls the blanket towards his nose like a mask and tucks their hands underneath the covers, fingers still entwined. “So mean Iwa-chan,” he mutters, tugging Iwaizumi the slightest bit closer to him.

“Good night, Oikawa,” Iwaizumi responds, doesn't pull away, and sinks deeper into his pillow willing his mind to calm down. But his mind runs laps around their conversation and hand-holding like a math problem he can’t solve, and math was not Iwaizumi’s best subject. He likes science because science makes sense. In school, he’d learn about how stars worked, and, when night came, he could trace his teacher’s lessons across the sky. 

Stars made sense, and so did the sun, the moon, and Godzilla (though Oikawa argues that Godzilla technically can’t exist because he’s too large, to which Iwaizumi retorts with the argument that dinosaurs just as large as Godzilla once existed and therefore Godzilla can also exist). What didn’t make sense is how he was still alive despite feeling like his face was on fire and why they were still holding hands.

As Iwaizumi’s thoughts slow to match the pace of the autumn night, his mind lands on a conclusion that he decides can’t be left unsaid. The idea of voicing his thoughts to a conscious Oikawa makes his heart beat too fast for his liking. He waits until he is certain that Oikawa is asleep.

He whispers into the dark with only the universe as his witness.

“Oikawa?”

No response.

“I just wanted you to know that I’d stay with you even if we didn’t get married.”

Iwaizumi closes his eyes and sighs as a weight is lifted off his chest. He can finally rest easy. As he slips into a deep slumber, weary from the events of the day, he thinks he feels Oikawa’s hand squeeze his a little tighter. Before he can question it, sleep overcomes him, and any memory he has of the event is lost in the stars.

Whether Oikawa was awake to respond to Iwaizumi’s confession or if that was the beginning of Iwaizumi’s dreams that night, only the universe knows. For the time being, only the universe needs to know, and the universe holds onto this exchange in the form of starlight. Though the two boys may never truly know how they made their first vows, their promise to each other lives amongst the stars, always shining down on them even when they can’t see it.

**Author's Note:**

> Thank you for reading!!!
> 
> I've been planning this for while, and I'm super excited to share it with everyone! I'm going to do my best to share Iwaoi falling deeper in love through the years with y'all <3
> 
> Thank you to my beta and Pauli for reading over this! You can check out Pauli's twitter [here](https://twitter.com/th3_crow_flies)  
> Thank you to Sayu for fueling this brainrot. You can find her on Twitter [here](https://twitter.com/kenmaniacc)
> 
> You're welcome to drop by and scream with me on [Twitter](https://twitter.com/an3m1c) anytime :)


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